Non-invasive baroreflex sensitivity assessment in heart failure patients with frequent episodes of non-sinus rhythm

Baroreflex sensitivity (BRS) has strong independent prognostic value in chronic heart failure (CHF). Reliable noninvasive BRS assessment requires the presence of uninterrupted sinus rhythm during several minutes; however, this condition is often not met in CHF patients due to the frequent occurrence of arrhythmias. Here, we present a novel method for the determination of a reliable BRS, by composing it from the multiple segments of sinus rhythm that occur throughout a BRS measurement session. This composite BRS is calculated from the multiple segment-based BRS values and their confidence intervals (CI) by using the best linear unbiased estimator (BLUE) method. For validation we used a set of recordings made in CHF patients who had >7 minutes of uninterrupted sinus rhythm, sufficient for the straightforward computation of a session BRS. These long recordings were then split into multiple short segments from which a multiple-segment- based BRS estimate was computed. As errors were small (1-5%) our proposed method appears to be feasible.